I have purchased a toroidal transformer to power my amplifier board. The transformer has 2 x 22volt secondary coils. One has red and black wires and the other has orange and yellow wires. My amp board has an AC input that states AC Dual with 3 input pins. I presume the input to the board is +-22volts with a centre reference. How would I wire the secondary wires of the transformer to feed this board. I think its refered to as a centre tap. All the rectification is done on the board.

Measure the AC voltage over the other two untied wires. If it is around 44V, plus or minus 20%, then the two tied together are your centre tap. If it is just a dribble then swap ONE of your secondary's wires over to the centre tap.